Studies of metal ion interaction with peptides are proposed with the long range objectives of understanding the role of metal ions in regulatory functions (activation or inhibition) of peptide hormones, neurotransmitters and antibiotics as well as the nature of metal ion transport and coordination in the body. Specific aims include (1) studies of new metal peptide complexes by exploration of additional coordination geometries and metal ions, (2) the characterization of Ni(III) peptides relatives to Ni(III) in enzymes, (3) metal ion interactions with biologically active peptides, (4) Cu(III,II) and Ni(III,II) activity in the dismutation of superoxide and in 02 activation, (5) the effect of solvents on metal peptide complexes, and (6) decomposition and substrate oxidation reactions of Ni(III) and Cu(III) peptides. A growing number of metal ions are known to react with enkephalins and other biologically active peptides. The nature, stability, oxidation state and kinetics of metal peptide complexes will be explored to help understand the biological transport, catalysis and toxicity of metal ions.